Flywheel magneto having short circuiting means



Aug. 18, 1964 w. 'o. HENSCHKE United States Patent 3,145,315 FLYWHEEL MAGNETO HAVING SHORT CIRCUETING MEANS William 0. Henschke, Longmeadow, Mass., assignor to R. E. Phelon Company, Inc, a corporation of Massachusetts Filed Aug. 27, 1962, Ser. No. 223,864 9 Claims. (Cl. 310-70) This invention relates to a high tension magneto of the flywheel type and particularly to such a magneto adapted for use with an internal combustion engine. A magneto embodying the invention has a stationary core structure and a rotatable field structure which rotates around the core structure.

In a magneto of the type mentioned, there is danger of a kick back in hand cranking it a spark occurs at too low a speed.

An object of the present invention is to provide a magneto having automatically operable means which serves to prevent this formation of a spark at low speeds and which permits normal functioning when the speed equals or exceeds a predetermined critical speed.

Another object of the invention is to provide a new and improved magneto of the type set forth which obtains this object without requiring current to pass through either bearings or sliding contacts.

Another object of the invention is to provide a new and improved magneto of the type set forth which obtains this object without requiring current to pass through either hearings or sliding contacts, said magneto including means to provide an automatic advance or retard should the external contacts of said magneto open later than the internal contacts of said magneto.

Another object is to provide a new and improved device of the type set forth that is an improvement over United States Patent No. 2,627,041.

Another object is to provide a new and improved magneto including means whereby the foregoing general objects may be attained.

Other objects and advantages of the invention will be apparent from the following description taken in connection with the accompanying drawings. It will be understood that changes may be made in the details of construction and arrangement of parts shown and described as the preferred form has been given by Way of illustration only.

Referring to the drawings:

FIG. 1 is a vertical transverse sectional View of a magneto embodying one form of the invention, said sectional view being taken on line 11 of FIG. 2 looking in the direction of the arrows;

FIG. 2 is a vertical longitudinal sectional view taken on line 22 of FIG. 1 looking in the direction of the arrows;

FIG. 3 is a vertical transverse sectional view of a magneto embodying a section form of the invention, said sectional View being taken on line 3-3 of FIG. 4 looking in the direction of the arrows; and

FIG. 4 is a vertical longitudinal sectional view taken on line 44 of FIG. 3 looking in the direction of the arrows.

Referring more particularly to the drawings wherein similar reference characters designate corresponding parts throughout the several views, the magneto shown including the invention comprises a non-rotatable core structure carried by a frame provided with a bushing 11 which provides a bearing for a rotatable shaft 12. Said shaft 12 may be an extension of the crankshaft of the engine with which the magneto is to be used, and, in any event, is rotated in timed relationship with the engine.

The core structure comprises a magnetic core 13 preferably laminated and so constructed and arranged as to provide a plurality of circularly spaced poles having arcuate faces concentric with the axis of the shaft 12 and equidistant therefrom. Said core 13 is connected with the frame 10 by means of pins 14. Primary and secondary windings or coils, grounded in the conventional manner, surround one of the poles of said core 13. As shown, the core 13 is provided withthree poles 15, 16 and 17, with the intermediate pole 16 being surrounded by the primary and secondary coils 1S and 19 respectively.

A circuit making and breaking means consisting of the breaker points 20 and 21 supported in part by the plate 22 is connected to the primary coil 18 by means of the insulated conductor 18a in the conventional manner.

The breaker point 20 is connected with the plate 22 and is, thus, grounded. The breaker point 21 is carried by a rocker arm 23 pivoted at 24 to the plate 22. The rocker arm 23 has an extension 25 which is engaged by a cam 26 mounted upon the shaft 12. A spring 27 serves to bias the rocker arm 23 to move the breaker point 20 into engagement with the breaker point 21 and said spring 27, or an auxiliary conductor associated therewith, serves to provide an electrical'connection between the conductor 18a and said breaker point 20. When the shaft 12 is rotated, the cam 26 oscillates the rocker arm 23 to move the point 20 and, thus, to make and break the electrical connection between the points 20 and 21 during each rotation of the rotor. A condenser 28 is connected in parallel With the breaker points 20 and 21 in the conventional manner.

The secondary coil 19 is connected to the spark plug of the engine in the usual manner.

The rotor of the magneto includes a flywheel 29 connected with the shaft 12 such as to be rotatable therewith. Said flywheel 29 is grounded by reason of its connection with the shaft 12.

The flywheel 29 illustrated herein is shown as having integral blades 30 adapted to cooperate with a housing, not shown, to provide a circulation of air.

The rotor of the magneto includes a field structure comprised of a permanent magnet 31 supported between the pole pieces 32 by said pole pieces 32.

In accordance with the present invention, a means is provided for short circuiting the circuit making and brealc ing means during the successive operations thereof. The short circuiting means is initially operative while the rotor is rotated at a relatively low speed. The short circuiting means includes a centrifugally movable element car: ried by the flywheel and constructed and arranged to move relatively thereto so as to cause the short circuiting means to be inoperative when the speed of rotor rotation equals or exceeds a predetermined critical speed.

This short circuiting means provided by the present invention does not require that current be carried through either bearings or sliding contacts. Furthermore, said short circuiting means herein provided includes means to provide an automatic advance or retard.

In the embodiment of the invention illustrated in FIGS. 1 and 2, the annular flange 33 of the flywheel is provided with a radial opening 34 in which is spring loaded a weight 35 by means of the coil compression spring 36, said spring 36 being held in operative position by means of the plug 37 positioned with the annular flange 33 adjacent to the side of said spring 36 opposite to that in contact with the weight 35. I

The weight 35 is provided at its-end opposite to that in contact with the spring 36 with an insulated portion 38. This insulated portion 38, thusly connected to said weight 35, serves to engage an arm or similar resilient member 39. Said arm 39, connected at one end to the plate 22 and electrically connected to the spring 27, serves I 3 to carry an electrical contact 4@ at its end farthest from its connection to said plate 22.

A shoulder is provided upon the inner surface of the flange 33 directly above the opening 34 such that the weight 35 cannot move inwardly to any substantial extent beyond the relative position shown in FIGS. 1 and 2.

The electrical contact 49 is positioned so as to make electrical contact with the contact 41 mounted upon the plate 42, which plate 42 is attached to the bracket fastened to the stator 43. Said contact 41 is mounted upon the plate 22.

The electrical contacts 49 and 41 are mounted in parallel with the electrical contacts and 21.

Thus, the operation of the short circuiting means provided by this invention does not require that current pass through either bearings or sliding contacts. Rather, the operation of the switch formed by the contacts 41 and 41 is controlled by the action of the insulated portion 38 of the spring loaded weight upon the arm 39 carrying the contact 40.

Thus, at starting or low speeds as determined by the action of centrifugal force and inertial force upon the spring 36, the external contacts 40 and 41 operate.

Furthermore, through the operation of this embodiment of the invention, automatic advance or retard is provided if the external contacts 40 and 41 open later than the internal contacts 26 and 21.

The embodiment of the invention illustrated in FIGS. 3 and 4 comprises a ball means 44 spring loaded within the radial opening 34 contained in the flange 33 of the flywheel by means of the coil compression spring 36, which spring 36 abuts its inner end against said ball means 44. The outer end of said spring 36 is held in position within the flange 33 by means of the plug 37.

The opening 34 is so formed that the ball 44 cannot move inwardly to any substantial extent beyond the relative position shown in FIGS. 3 and 4.

A single electrical contact 45 is connected to the plate 22 and electrically connected to the spring 27 by means of the arm 46. Said arm 46, in connecting said contact 45 to the plate 22, passes over the ball means 44 when the spring 34 is in uncompressed position such that the force of said ball means 44 upon the arm 46 tends to force the contact 45 into engagement with the stator 43, which stator is connected to the plate 22.

Said stationary bracket or stator 43 serves to close the circuit with the contact 45 when said contact 45 is in engagement with the stator 43. If the switch formed by the stator 43 and the contact 45 opens later than that formed by the contacts 29 and 21, an automatic advance or retard is provided.

The embodiment of the invention shown in FIGS. 1 and 2 operates as below described.

During each rotation of the rotor at low speed, the insulated portion 38 of the weight 35 engages the arm 39 and forces said arm 39 upwardly, thereby forcing the contact 40 on the end of said arm 39 into engagement with the contact 41 mounted upon the plate 42. During the normal rotation of the rotor and due to the rotation of the cam 26, the breaker point 21 separates from the breaker point 20. The separation of the breaker points normally serves to break the circuit in the primary coil and to produce a spark forming voltage in the secondary coil. However, with the contact 40 in engagement with the contact 41 a short circuit is provided across the breaker points, the said short circuit including the contacts 40 and 41. By reason of the short circuit, the circuit in the primary coil is not broken and no spark is formed.

When the speed of rotation of the rotor equals or exceeds a predetermined critical speed, which may be approximately 500 rpm, the weight 35 and its carried insulated piece 38 move outwardly by centrifugal action such as to overcome the pressure exerted by the spring 36 and said spring 36 is thereby compressed. When the weight 35 and insulated piece 38 have been moved outwardly by centrifugal action as described, said insulated piece 38 is no longer in position to engage the arm 39 and to, thus, force the contact 46 into engagement with the contact 41 and the short circuiting means becomes inoperative. With the short circuiting means inoperative, the circuit is broken in the normal manner at the breaker points 20 and 21.

The form of the invention illustrated in FIGS. 3 and 4 operates in a similar manner.

From the foregoing it will be seen that I have provided new and improved means for obtaining all of the objects and advantages of the invention.

1 claim:

1. A flywheel magneto comprising in combination, a rotor including a flywheel and also including a field structure carried by the flywheel, a stator including a core having a plurality of circularly spaced pole faces in cooperative relationship with the field structure of the rotor and also including a primary coil and a secondary coil on the core, the said secondary coil being connectible with a sparking device, means operable during each rotation of the rotor for making and breaking a circuit through the said primary coil and normally serving upon the breaking of the said circuit to produce a spark forming voltage in the secondary coil, and a means operative at rotor speeds below a predetermined critical speed for short circuiting the said circuit making and breaking means, the said short circuiting means including a centrifugally movable element carried by the flywheel and constructed and arranged to move relatively thereto when the speed of rotor rotation equals or exceeds the said critical speed so as to cause the short circuiting means to be then inoperative, said short circuiting means also including a contact member connected to and carried by the stator, said contact member being operatively associated with said centrifugally movable element and actuated thereby.

2. A flywheel magneto comprising in combination, a rotor including a flywheel and also including a field structure carried by the flywheel, a stator including a core having a plurality of circularly spaced pole faces in cooperative relationship with the field structure of the rotor and also including a primary coil and a secondary coil on the core, the said secondary coil being connectible with a sparking device, means operable during each rotation of the rotor for making and breaking a circuit through the said primary coil and normally serving upon the breaking of the said circuit to produce a spark forming voltage in the secondary coil, and a means operative at rotor speeds below a predetermined critical speed for short circuiting the said circuit making and breaking means, the said short circuiting means including a centrifugally movable element carried by the flywheel and constructed and arranged to move relatively thereto when the speed of rotor rotation equals or exceeds the said critical speed so as to cause the short circuiting means to be then inoperative, said short circuiting means also including a contact member operatively associated with said centrifugally movable element and actuated thereby, said contact member comprising a resilient member having one end fixed and having a contact portion adjacent its free end and said member having an intermediate portion adapted to engage said centrifugally movable element, and a member carried by said stator and directly connected thereto engaged by said contact member.

3. A flywheel magneto comprising in combination, a rotor including a flywheel and also including a field structure carried by the flywheel, a stator including a core having a plurality of circularly spaced pole faces in cooperative relationship with the field structure of the rotor and also including a primary coil and a secondary coil on the core, the said secondary coil being connectible with a sparking device, means operable during each rota tion of the rotor for making and breaking a circuit through the said primary coil and normally serving upon the breaking of the said circuit to produce a spark forming voltage in the secondary coil, and a means operative at rotor speeds below a predetermined critical speed for short circuiting the said circuit making and breaking means, the said short circuiting means including a centrifugally movable element carried by the flywheel and constructed and arranged to move relatively thereto when the speed of rotor rotation equals or exceeds the said critical speed so as to cause the short circuiting means to be then inoperative, said short circuiting means including switch means carried by and connected to said stator, said switch means being actuated by said centrifugally movable element.

4. A flywheel magneto comprising in combination, a rotor including a flywheel and also including a field structure carried by the flywheel, a stator including a core having a plurality of circularly spaced pole faces in cooperative relationship with the field structure of the rotor and also including a primary coil and a secondary coil on the core, the said secondary coil being connectible with a sparking device, means operable during each rotation of the rotor for making and breaking a circuit through the said primary coil and normally serving upon the breaking of the said circuit to produce a spark forming voltage in the secondary coil, and a means operative at rotor speeds below a predetermined critical speed for short circuiting the said circuit making and breaking means, the said short circuiting means including a centrifugally movable element carried by the flywheel and constructed and arranged to move relatively thereto when the speed of rotor rotation equals or exceeds the said critical speed so as to cause the short circuiting means to be then inoperative, said short circuiting means including switch means carried by and connected to said stator and actuated by said centrifugally movable element, said switch means comprising a contact carrying resilient member.

5. A flywheel magneto comprising in combination, a rotor including a flywheel and also including a field structure carried by the flywheel, a stator including a core having a plurality of circularly spaced pole faces in cooperative relationship with the field structure of the rotor and also including a primary coil and a secondary coil on the core, the said secondary coil being connectible with a sparking device, means operable during each rotation of the rotor for making and breaking a circuit through the said primary coil and normally serving upon the breaking of the said circuit to produce a spark forming voltage in the secondary coil, and means operative at rotor speeds below a predetermined critical speed for short circuiting the said circuit making and breaking means, the said short circuiting means including a centrifugally movable element carried by the flywheel and constructed and ar ranged to move relatively thereto when the speed of rotor rotation equals or exceeds the said critical speed so as to cause the short circuiting means to be then inoperative, said short circuiting means including switch means actuated by said centrifugally movable element, said switch means comprising a contact carrying resilient member, said resilient member having one end fixed and having a contact adjacent its free end, and a member carried by and directly connected to said stator and engaged by said contact when the speed of rotor rotation is less than said critical speed.

6. A flywheel magneto comprising in combination, a rotor including a flywheel and also including a field structure carried by the flywheel, a stator including a core having a plurality of circularly spaced pole faces in cooperative relationship with the field structure of the rotor and also including a primary coil and a secondary coil on the core, the said secondary coil being connectible with a sparking device, means operable during each rotation of the rotor for making and breaking a circuit through the said primary coil and normally serving upon the breaking of the said circuit to produce a spark forming voltage in the secondary coil, and a means operative at rotor speeds below a predetermined critical speed for short circuiting the said circuit making and breaking means, the said short circuiting means including a centrifugally movable element carried by the flywheel and constructed and arranged to move relatively thereto when the speed of rotor rotation equals or exceeds the said critical speeds so as to cause the short circuiting means to be then inoperative, said short circuiting means including switch means actuated by said centrifugally movable element, said switch means comprising a contact carrying resilient member, said resilient member having one end fixed and having a contact adjacent its free end, and a contact carried by and directly connected to said stator engaging said contact on said resilient member.

7. A flywheel magneto comprising in combination, a rotor including a flywheel and also including a field structure carried by the flywheel, a stator including a core having a plurality of circularly spaced pole faces in cooperative relationship with the field structure of the rotor and also including a primary coil and a secondary coil on the core, the said secondary coil being connectible with a sparking device, means operable during each rotation of the rotor for making and breaking a circuit through the said primary coil and normally serving upon the breaking of the said circuit to produce a spark forming voltage in the secondary coil, and a means operative at rotor speeds below a predetermined critical speed for short circuiting the said circuit making and breaking means, the said short circuiting means including a centrifugally movable element carried by the flywheel and constructed and arranged to move relatively thereto when the speed of rotor rotation equals or exceeds the said critical speed so as to cause the short circuiting means to be then inoperative, said short circuiting means including a contact carrying member operatively associated with said centrifugally movable element and actuated thereby, said centrifugally movable element having an insulated portion adapted to engage said contact member, and a member connected to said stator and adapted to engage said contact carried by said contact carrying member when the speed of rotor rotation is less than said critical speed. 8. A flywheel magneto comprising in combination, a rotor including a flywheel and also including a field structure carried by the flywheel, a stator including a core having a plurality of circularly spaced pole faces in cooperative relationship with the field structure of the rotor and also including a primary coil and a secondary coil on the core, the said secondary coil being connectible with a sparking device, means operable during each rotation of the rotor for making and breaking a circuit through the said primary coil and normally serving upon the breaking of the said circuit to produce a spark forming voltage in the secondary coil, and a means operative at rotor speeds below a predetermined critical speed for short circuiting the said circuit making and breaking means, the said short circuiting means including a centrifugally movable element carried by the flywheel and constructed and arranged to move relatively thereto when the speed of rotor rotation equals or exceeds the said critical speed so as to cause the short circuiting means to be then inoperative, said short circuiting means including switch means actuated by said centrifugally movable element, said centrifugally movable element having an insulated portion adapted to engage said switch means. 9. A flywheel magneto comprising in combination, a rotor including a flywheel and also including a field structure carried by the flywheel, a stator including a core having a plurality of circularly spaced pole faces in cooperative relationship with the field structure of the rotor and also including a primary coil and a secondary coil on the core, the said secondary coil being connectible with a sparking device, means operable during each rotation of the rotor for making and breaking a circuit through the said primary coil and normally serving upon the breaking of the said circuit to produce a spark forming voltage in the secondary coil, and a means operative at rotor speeds below a predetermined critical speed for short circuiting the said circuit making and breaking means, the said short circuiting means including a centrifugally mov able element carried by the flywheel and constructed and arranged to move relatively thereto when the speed of rotor rotation equals or exceeds the said critical speed so as to cause the short circuiting means to be then inoperative, said short circuiting means including switch means actuated by said centrifugally movable element,

said switch means comprising a contact carrying resilient member and a member directly connected to said stator References Cited in the file of this patent UNITED STATES PATENTS 2,627,041 Phelon June 27, 1953 

1. A FLYWHEEL MAGNETO COMPRISING IN COMBINATION, A ROTOR INCLUDING A FLYWHEEL AND ALSO INCLUDING A FIELD STRUCTURE CARRIED BY THE FLYWHEEL, A STATOR INCLUDING A CORE HAVING A PLURALITY OF CIRCULARLY SPACED POLE FACES IN COOPERATIVE RELATIONSHIP WITH THE FIELD STRUCTURE OF THE ROTOR AND ALSO INCLUDING A PRIMARY COIL AND A SECONDARY COIL ON THE CORE, THE SAID SECONDARY COIL BEING CONNECTIBLE WITH A SPARKING DEVICE, MEANS OPERABLE DURING EACH ROTATION OF THE ROTOR FOR MAKING AND BREAKING A CIRCUIT THROUGH THE SAID PRIMARY COIL AND NORMALLY SERVING UPON THE BREAKING OF THE SAID CIRCUIT TO PRODUCE A SPARK FORMING VOLTAGE IN THE SECONDARY COIL, AND A MEANS OPERATIVE AT ROTOR SPEEDS BELOW A PREDETERMINED CRITICAL SPEED FOR SHORT CIRCUITING THE SAID CIRCUIT MAKING AND BREAKING MEANS, THE SAID SHORT CIRCUITING MEANS INCLUDING A CENTRIFUGALLY MOVABLE ELEMENT CARRIED BY THE FLYWHEEL AND CONSTRUCTED AND ARRANGED TO MOVE RELATIVELY THERETO WHEN THE SPEED OF ROTOR ROTATION EQUALS OR EXCEEDS THE SAID CRITICAL SPEED SO AS TO CAUSE THE SHORT CIRCUITING MEANS TO BE THEN INOPERATIVE, SAID SHORT CIRCUITING MEANS ALSO INCLUDING A CONTACT MEMBER CONNECTED TO AND CARRIED BY THE STATOR, SAID CONTACT MEMBER BEING OPERATIVELY ASSOCIATED WITH SAID CENTRIFUGALLY MOVABLE ELEMENT AND ACTUATED THEREBY. 